During a similar discussion in july ([1]) about u-turn, another existing tag was provided: http://wiki.openstreetmap.org/wiki/Key:overtaking It's about "overtaking" but the description could be easily enhanced with u-turn restriction as well. Pieren [1] http://gis.19327.n5.nabble.com/Tagging-u-turn-restriction-with-continuous-painted-line-tt5714828.html